Sliding clasp fastener

ABSTRACT

An elongated, plastic slide fastener stringer of the modified, continuous helix type in which each fastener element extends substantially in a plane transverse to the direction of stringer elongation, and the elements are longitudinally connected by integral portions of the helix. Each element consists of a substantially U-shaped front reverse turn formed with a coupling surface and a substantially U-shaped rear reverse turn, the reverse turns each having a first terminal part and a second terminal part, the first terminal parts being integrally joined to each other, and the second terminal parts being integrally joined to respective connecting portions. A protuberance on the second terminal part of the rear reverse turn is aligned in the direction toward the coupling surface and beyond the connecting portion joined to the second terminal part of the reverse turn for abutting engagement, and provides anchorage for sewing thread fastening the stringer to a support.

United States Patent [191 Popovitsch SLIDING CLASP FASTENER Ernst Popovitsch, Stuttgart-Steckfeld, Germany [73] Assignee: Dr. Karl F. Nagele Feinmaschinenbau, Stuttgart-Hohenheim, Germany [22] Filed: 'June 8, 1971 [21] App]. No.: 151,008

Related US. Application Data [62] Division of Ser. No. 33,469, April 30, 1970, Pat. No.

[75] Inventor:

[111 3,800,367 [4 1 Apr. 2, 1974 Porepp 24/205.l C Frohlich 24/205.13 C

Primary Examiner-Bernard A. Gelak 57] ABSTRACT An elongated, plastic slide fastener stringer of the modified, continuous helix type in which each fastener element extends substantiallyin a plane transverse to the direction of stringer elongation, and the elements are longitudinally connected by integral portions of the helix. Each element consists of a substantially U- shaped front reverse turn formed with a coupling surface and a substantially U-shaped rear reverse turn, the reverse turns each having a first terminal part and a second terminal part, the first terminal parts being integrally joined to each other, and the second terminal parts being integrally joined to respective connecting portions. A protuberance on the second terminal part of the rear reverse turn is aligned in the direction toward the coupling surface and beyond the connecting portion joined to the second terminal part of the reverse turn for abutting engagement, and provides anchorage for sewing thread fastening the stringer to a support.

1 Claim, 9 Drawing Figures PATENTEDAPR 2 1974 saw a or 4 INVENTOR. 2 0 Papal/#564 BY Wm WM erwm,

SLIDING CLASP FASTENER This application is a division of the copending application Ser. No. 33,469, filed on Apr. 30, 1970, and now US. Pat. No. 3,666,853.

The present invention relates to a continuous stringer for a sliding clasp fastener made from a helical of a plastics material. I

The construction of such a stringer, which comprises a plurality of fastener elements joined by interconnecting portions and made from a filament that is basically coiled, preferably into the shape of a helix, necessitates a particularly strong deformation, which exceeds the amount at present usual for making such stringers.

It is known to manufacture sliding clasp fastener stringers from a plastics material in the shape of deformed helices in such a manner that, the connections between the individual coupling elements of the stringer, i.e. the inclined parts or portions, are located in the rearward area of the helix remote from the coupling surfaces. Should, however, the inclined parts which connect the coupling elements together not run in the rearward region of the helix but in the central area of the elements, i.e. between the front and rear re verse turns of the element, the known deformation measures are not sufficient for economic manufacture.

It is an object of the present invention to bring about by simple means, a particularly strong deformation of a helix into a closed shape of the described configuration. p

More specifically, the invention provides an improvement in a stringer for a sliding clasp fastener consistingof a continuous strand ofplastics material shaped into convolutions of periodically varying inclination, each convolution constituting a fastener element substantially extending in a plane and respective parts of two connecting portions transverse to said plane sequentially connecting the elements in an elongated row, the strand in each element constituting a front reverse turn formed with a coupling surface and a rear reverse turn. The reverse turns each have a first and a second terminal part, the first terminalparts' being integrally joined to each other, and the second terminal parts being integrally joined to respective connecting portions.

' The improvement contributed by this invention to the afore-described, known stringer resides in a protuberance on one of the second terminal parts of each element which projects beyond the associated connecting portion and is aligned longitudinally of the row with the other second terminal part of the element.

In the embodiment of the invention more specifically disclosed hereinbelow, the protuberance projects from the second terminal part of 'the rear reverse turn toward the coupling surface of the element, and the connecting portions are elongated and longitudinally aligned in the direction of elongation of the row.

The invention also consists including clasp fasteners made from such stringers.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which show certain aspects thereof by way of example, and in which:

FIG. 1 shows a side view of the complete apparatus,

FIG. 2 shows a side view of a part of the apparatus being used for withdrawing the helically shaped stringer for deforming and stamping, part of the apparatus being removed to make the showing clearer,

FIG. 3 shows a section through the stamping device along the line III-III of FIG. 2,

FIG. 4 shows a plan view of part of the apparatus according to FIG. 2,

FIGS. 5 and 6 show cross-sections through various parts of the coiling mandrel,

and fed into a magnetically heated winding head 3, in

a stationary part 5 of which is secured a coiling mandrel 6. The plastics filament 1 is fed through a rotating ring 4 of the winding head 3 and wound into a helix about the fixed winding mandrel 6. The convolutions thrust themselves forward and arrive between preforming wheels 7 and 8 (FIG. 4). These latter are peripherally provided with transverse gaps 9 at predetermined intervals depending upon the desired spacing of the fastener elements. A gap is provided between the preforming wheels 7 and 8 which corresponds only to the width of the coiling mandrel6 at its end 6b which is tapered. Thus, the tapered and 6b of the mandrel is supported from opposite'sides, whilst the coil passes through and the arrangement ensures a diametrical pressure on the convolutions thus assisting in forming coupling surfaces 14, as the helix passes between the wheels.

The effective stamping of the coupling surfaces 14,

however, also necessitates a stamping die 15 (FIGS. 1

and 2). An adjustable backingblock 16 which covers considerably more windings than the die 15, supports the stamping pressure and also the mandrel at 6b. By adjusting the backing block 16 by means of an eccentric disc 17, the height of the coupling surfaces 14 can be adjusted to any desired degree. Since the coupling surface 14 is stamped before the fixing operation, i.e. before the helix enters into a heated wheel or drum 18, the amount of material which is needed for the inclined portion 11 or 19 connecting the fastener elements has to be taken into account during the stamping operation. This extra material is made available during winding, due to the cross'sectional shape of the thicker part 6a of the mandrel. The mandrel is tapered at 6b to a decreased cross-section in the reception area of the preforming wheels 7 and 8. An annular groove 10 in the preforming wheel 8 offers room for the connecting portion 1 l(FIG. 2) as yet lying at an oblique angle. A resilient pointed braking member 23 presses the convolutions of the helix 12in the direction of the preforming wheel 8, so that they are engaged first by the preforming wheel 8. By this arrangement, moreover, the convolution is slightly offset so that its diametrical portion facing the preforming wheel 7 can engage therein more efficiently and without error.

The preforming so achieved, with the obliquely inclined portions 1 l, is not permanent since the material can still spring back.

The end 6b of the winding mandrel leads tangentially into the heated shaping wheel or drum 18. This latter consists of discs 18a 18b and 180 (FlG. 8). The disc 18a is provided with cross-pieces 20 whose distance from one another corresponds exactly to the desired spacing of the elements in the finished fastener. The cross-pieces 20 are of the same height as the stringer. The disc 18c has pins 21, which correspond to the spacing of the cross pieces 20 on the disc 18a but are only as high as the inclined portions 19 of the stringer allow. The base of an annular groove 22 formed between the discs 18a and 18c is formed by the peripheral surface of the central disc 18b. This groove receives the end 6b of a mandrel and also the coupling surfaces 14. It also offers space for the stripper 24.

The ultimate shape and direction of the connecting portions 19 is achieved in the-heated shaping wheel 18. To this end, toothed discs 25 and 26 are arranged on the periphery of the heating wheel 18. These latter have teeth 27, which run synchronously with the pins 21. The inclined portion 19 is formed and directed between the teeth 27 and the pins 21. Slightly inclined surfaces 28 on the pins 21 effect formation of a protuberance 29 on the inclined portions 19 of the stringer. This latter offers the advantage that when loading the stringer sewn to its carrier tape, the seam cannot slip. The protuberance 29 is also used for anchoring the sewing thread.

An exact shape and direction of the inclined portion 19 connecting the elements can best be achieved by rerolling, by means of additional toothed discs similar to 25, 26, one behind the other. The shape of the teeth 27 then differs from disc to disc. The teeth 27 of the first disc 25 are slender and pointed and those of the last one 26 rather blunt.

The stringer is withdrawn from the heated wheel by means of the stripper 24. At the exit point, the stringer is initially cooled by a stream of air, ensuring the correct spacing of the elements of the stringer. Complete cooling of the stringer is effected in the open air. It is advantageous to apply a slight stress by a light roller 30 for this purpose, so that twisting is avoided as far as possible. In order to decrease or remove the twist on a finished fastener, it is advisable to coil one stringer of the fastener, for example, to the right and the other to the left.

It has proven advantageous to double up the machines side by side, for which purpose a stringer closing device 31 is provided at the end of the machines to draw both the produced stringers together to form a completed chain. This has the advantage that complete cooling off can occur in the closed position of the two in the manner described above and attached to respec-' tive tapes 34 by means of sewing threads 35 is partly shown in FIG. 9. The sewing threads pass over the connecting portions 19 and are held in position by the protuberances 29, thereby impeding disengagement of the I coupling surfaces 14.

Each illustrated stringer element consists of an approximately U-shaped front reverse turn 40 carrying the coupling surface 14 and similarly shaped rear reverse turn 41. Respective first terminal parts 40a, 41a of the two reverse turns are integrally joined to each other, and the second terminal parts 40b, 41b are integrally joined to respective connecting portions 19, 19a. The protuberance 29 projects from the second terminal part 41b of the rear transverse turn 41 generally in a direction toward the coupling surface 14 beyond the associated connecting portion 19a and normally abuts against the second terminal part 40b of the front referse turn 40 in the direction of stringer elongation.

What we claim is:

1. ln a stringer for a sliding clasp fastener consisting of a continuous strand of plastics material shaped into convolutions of periodically varying inclination, each convolution constituting a fastener element substantially extending in a plane and respective parts of two connecting portions transverse to said plane and sequentially connecting said elements in an elongated row, said strand in each element constituting a substantially U-shaped front reverse turn formed with a coupling surface and a substantially U-shaped rear reverse turn, said reverse turns each having a first and second terminal part, said first terminal parts being integrally joined to each other, and said second terminal parts being integrally joined to respective connecting portions, the improvement which comprises: a protuberance on the second terminal part of the rear reverse turn of each element, said protuberance projecting generally in a direction toward the coupling surface of said element and beyond the connecting portion joined to said second terminal part of said rear reverse turn for abutting engagement with the second terminal part of the front reverse turn of said element. 

1. In a stringer for a sliding clasp fastener consisting of a continuous strand of plastics material shaped into convolutions of periodically varying inclination, each convolution constituting a fastener element substantially extending in a plane and respective parts of two connecting portions transverse to said plane and sequentially connecting said elements in an elongated row, said strand in each element constituting a substantially U-shaped front reverse turn formed with a coupling surface and a substantially U-shaped rear reverse turn, said reverse turns each having a first and second terminal part, said first terminal parts being integrally joined to each other, and said second terminal parts being integrally joined to respective connecting portions, the improvement which comprises: a protuberance on the second terminal part of the rear reverse turn of each element, said protuberance projecting generally in a direction toward the coupling surface of said element and beyond the connecting portion joined to said second terminal part of said rear reverse turn for abutting engagement with the second terminal part of the front reverse turn of said element. 